1. Year 7 Variation Survey

2. What Can You Do With a Table of Data? Start with some tally charts Use graphs to show patterns Add trendlines where needed You can describe a set of data Or you can compare two sets of data to see if they vary together

3. Discontinuous Variables Clear categoriesShown on bar charts Gaps between the bars!e.g. Eye colour, shoe size

4. Continuous Variables Values on a rangeShown on histograms No gaps between the bars!e.g. Height, mass Consider the average and the spread

5. Connections Between Variables These can be shown on scatter graphs Add lines of best fit

6. Other Graph Types Pie charts can be good for discontinuous data Split-bar charts can be good to look for connections between discontinuous data

7. Questions You Could Ask Describe the pattern of swimming skills in the class Are mass and height connected? Are girls taller than boys? Do people with large feet also have large hands? What’s the class weight pattern? Is the pattern for boys the same as for girls?

8. More Questions Do tall people have large feet? What’s the pattern of tongue rolling? Is tongue rolling connected to earlobes? Do good swimmers have large feet/hands? Is eye colour connected to hair colour? Can you think of any more?

9. Descriptions and Explanations Looking at patterns is not the same as explaining them. Can you suggest reasons for any patterns or connections you have spotted?

10. Correlations Scatter graphs may show positive or negative correlations, or they may show no correlation at all. Remember a correlation does not always show a cause. For example, big feet does not cause you to have big hands. What other reason(s) might there be for a correlation?

11. Sampling Our class data probably does not represent all year 7 very well. Why not? Would Benton Park year 7 be a good sample of all 11-12 year olds? Explain your answer. How could we look at these patterns for all 11-12 year olds? Explain the difference between primary and secondary data.